Dunning-Kruger effect

When someone is bad/stupid/ignorant in a field, and thinks they are great/good/guru/expert. This normally happens due to people not having enough knowledge in that field to even know that they are bad at this field. A great place to find and report these people is at /r/iamverysmart

Dude1 : I am an expert in math
Dude2 : You are falling to the dunning-kruger effect (seriously wtf why do I have to include the word in this), all you know is how to add and subtract